DTC B2624 Display Dimming PWM Input Circuit Open. Chevrolet PJJ 2000

For 1990-2009 cars
Lighting Systems Components
Instrument Panel Dimmer Switch and Body Control Module

### Circuit Description

The body control module (BCM) supplies voltage to the instrument panel dimmer switch through CKT 230. The dimmer switch varies the voltage and returns the new voltage to the BCM through CKT 719. The BCM uses this voltage to determine the illumination level of the instrument panel lamps.

### Conditions for Running the DTC

The park lamp input to the BCM is active (park or headlamps on).

### Conditions for Setting the DTC

Any of the following conditions will set this DTC:

• | CKT 230 is open for 5 seconds.

• | CKT 719 is open for 5 seconds.

• | CKT 230 is shorted to battery for 5 seconds.

### Action Taken When the DTC Sets

The illumination of the instrument panel lamps is forced to full intensity.

### Conditions for Clearing the DTC

• | A current DTC B2624 will clear when the malfunction is no longer present.

• | All BCM history codes clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.

### Diagnostic Aids

• | If CKT 230 becomes shorted to ground, no DTC will be set but the instrument panel lamps will be at full intensity.

• | If CKT 719 is shorted to battery positive voltage, a direct short to ground is the result.

• | If the DTC is a history DTC, the problem may be intermittent. Try performing the tests while wiggling the wiring and connectors. This can often cause the malfunction to appear.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. The normal operating voltage of the instrument panel dimmer switch is .5-11.5 volts.

2. If the value is above 11.5 volts, with the sensor disconnected, an open or short to voltage exists. If the value is below .5 volts, a short to ground exists.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Lighting Systems Diagnostic System Check? | -- | Go to Step 2 | Go to A Diagnostic System Check-Lighting Systems

2

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the INTERIOR DIM POT data parameter in the LAMP STATUS data list.

Does the scan tool indicate that the INTERIOR DIM POT parameter is within the specified range?

.5-11.5 volts

Go to Step 5

Go to Step 3

3

1. Turn OFF the ignition.
2. Disconnect the instrument panel dimmer switch.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the INTERIOR DIM POT data parameter.

Does the scan tool indicate that the INTERIOR DIM POT data parameter is greater than the specified value?

11.5 volts

Go to Step 5

Go to Step 4

4 | Test the signal circuit and the ground circuit of the instrument panel dimmer switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 6
5 | Test the signal circuit and the ground circuit of the instrument panel dimmer switch for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7
6 | Inspect for poor connections at the harness connector of the instrument panel dimmer switch. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8
7 | Inspect for poor connections at the harness connector of the body control module. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9
8 | Replace the instrument panel dimmer switch. Refer to Instrument Panel Dimmer Switch Replacement. Did you complete the replacement? | -- | Go to Step 10 | --
9 | Important: Perform the set up procedure for the body control module. Refer to BCM Programming/RPO Configuration in Body Control System. Replace the body control module. Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 10 | --

10

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK